H UMAN OVARY 205 



3. The zona vasculosa. (Note the unusual thickness of the 

 vascular walls and the irregular outlines on section, on account of 

 their tortuous course.) 



(H.) 



4. The Graafian follicles. () Their diameter, varying from 

 25 /* when young to 5 or 10 mm. when mature, (b) The mem- 

 brana propria. (This is difficult to separate from the stroma 

 of the ovary itself, except in more mature follicles than shown 

 in the section, (c) The membrana granulosa. (This, in general, 

 appears to be the outer layer of the follicle, on account of the 

 difficulty of separating the membrana propria from the stroma 

 proper of the ovary. Note that it is composed, in the smaller and 

 less mature follicles, of pavement cells, and that the cells become 

 thicker with maturation, until columnar cells in a single layer 

 result, (d) The ova. (These are contained within the follicles, 

 excepting that they may have become detached during manipula- 

 tion of the section, and occupy the greater part of the follicles.) 

 (e) The zona pellucida (the thin wall of the ovum). (/) The 

 discus proligerus. (This will be recognized as a mass of polyhe- 

 dral cells, connecting the ovum at one side with the columnar celts 

 of the membrana granulosa. These cells will proliferate later 

 in the development, and completely enclose the ovum.) (g) The 



.germinal vesicle. (Contained within the ovum. The contents 

 appear granular ; it, as well as the ovum, is fibrillated ; but this 

 demonstration cannot be made, excepting the animal be killed for 

 the purpose, and the tissue elements fixed, before changes, which 

 quickly follow death, occur.) (h) The germinal spot. (Appear- 

 ing as a small dot within the germinal vesicle. The ovum pre- 

 sents the characteristics of what it indeed is a typical cell, with 

 wall, body, nucleus, and nucleolus.) 



5. The corpus luteum. (The example shown in the drawing 

 was developed after the contents of the Graafian follicle, which it 

 represents, had suffered impregnation ; and it has arrived at the 

 later stage of the series of the phenomena connected with its 

 development the stage of cicatrization. The cicatricial tissue, to 

 which the letter K points, indicates the remains of the membrana 

 granulosa. Outside is seen the thickened membrana propria, while 

 among the contents will be found pigment -granules and fat -glob- 

 ules, imbedded in a structureless, gelatinous stroma. This 

 material results from changes in the clot of blood effused after 

 the escape of the ovum.) 



